//
// Locator.h
//
// Library: XML
// Package: SAX
// Module:  SAX
//
// SAX Locator Interface.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef SAX_Locator_INCLUDED
#define SAX_Locator_INCLUDED


#include "Poco/XML/XML.h"
#include "Poco/XML/XMLString.h"


namespace Poco
{
namespace XML
{


    class XML_API Locator
    /// Interface for associating a SAX event with a document location.
    ///
    /// If a SAX parser provides location information to the SAX application, it does so by
    /// implementing this interface and then passing an instance to the application using the
    /// content handler's setDocumentLocator method. The application can use the object to obtain
    /// the location of any other SAX event in the XML source document.
    ///
    /// Note that the results returned by the object will be valid only during the scope of each
    /// callback method: the application will receive unpredictable results if it attempts to use
    /// the locator at any other time, or after parsing completes.
    ///
    /// SAX parsers are not required to supply a locator, but they are very strongly encouraged to
    /// do so. If the parser supplies a locator, it must do so before reporting any other document
    /// events. If no locator has been set by the time the application receives the startDocument event,
    /// the application should assume that a locator is not available.
    {
    public:
        virtual XMLString getPublicId() const = 0;
        /// Return the public identifier for the current document event.
        ///
        /// The return value is the public identifier of the document entity or of the external
        /// parsed entity in which the markup triggering the event appears.

        virtual XMLString getSystemId() const = 0;
        /// Return the system identifier for the current document event.
        ///
        /// The return value is the system identifier of the document entity or of the external
        /// parsed entity in which the markup triggering the event appears.
        ///
        /// If the system identifier is a URL, the parser must resolve it fully before passing
        /// it to the application. For example, a file name must always be provided as a
        /// file:... URL, and other kinds of relative URI are also resolved against their bases.

        virtual int getLineNumber() const = 0;
        /// Return the line number where the current document event ends.
        /// Lines are delimited by line ends, which are defined in the XML specification.
        ///
        /// Warning: The return value from the method is intended only as an approximation for
        /// the sake of diagnostics; it is not intended to provide sufficient information to
        /// edit the character content of the original XML document. In some cases, these "line"
        /// numbers match what would be displayed as columns, and in others they may not match the
        /// source text due to internal entity expansion.
        ///
        /// The return value is an approximation of the line number in the document entity or external
        /// parsed entity where the markup triggering the event appears.
        ///
        /// If possible, the SAX driver should provide the line position of the first character after
        /// the text associated with the document event. The first line is line 1.

        virtual int getColumnNumber() const = 0;
        /// Return the column number where the current document event ends.
        /// This is one-based number of characters since the last line end.
        ///
        /// Warning: The return value from the method is intended only as an approximation
        /// for the sake of diagnostics; it is not intended to provide sufficient information
        /// to edit the character content of the original XML document. For example, when lines
        /// contain combining character sequences, wide characters, surrogate pairs, or bi-directional
        /// text, the value may not correspond to the column in a text editor's display.
        ///
        /// The return value is an approximation of the column number in the document entity or external
        /// parsed entity where the markup triggering the event appears.
        ///
        /// If possible, the SAX driver should provide the line position of the first character after
        /// the text associated with the document event. The first column in each line is column 1.

    protected:
        virtual ~Locator();
    };


}
} // namespace Poco::XML


#endif // SAX_Locator_INCLUDED
